It is known to mount a plurality of spray nozzle assemblies along a liquid supply boom, up to twenty feet or more in length, which is pulled by a tractor or is part of a self-contained vehicle, with the discharging spray patterns of the nozzles in partially overlapping relation to each other to create a wide spray curtain. To achieve substantially uniform liquid distribution throughout the spray curtain, it is necessary that the spray nozzles be mounted on the spray boom at such intervals that the discharging sprays overlap in a determined fashion. Excessive spacing between the spray nozzles can result in insufficient liquid distribution between adjacent discharging sprays, and too close of nozzle spacing can result in excessive liquid distribution in the overlapping spray patterns. Because of the necessity for using a multiplicity of spray nozzles, boom mounted spraying systems are expensive. Booms also can be cumbersome to pull and manipulate during spraying.
Additionally, many applications exist where boom spraying is impractical or ineffective. For example, rugged terrain or other obstacles or impediments can restrict boom lengths. This reduces the cost effectiveness of boom spraying in these applications. If such obstacles or impediments are severe enough, manual spraying using handheld spray guns, which is both inaccurate and costly, could be required.
While proposals have been made for using a single spray nozzle to direct a relatively wide spray pattern in order to eliminate the necessity for a multiplicity of spray nozzles and the long supporting boom, such prior proposals have been relatively expensive and have not been effective for discharging sprays with uniform liquid distribution.